The UK
Department of Trade and Industry (now the Department of
Business, Enterprise and Regulatory Reform)
characterizes nitrosamines as more toxic in more animal
species than any other category of chemical carcinogen (i).
Nitrosamines are common in cosmetics, but because they
are impurities, they are not listed on product labels.

Products That May Contain Nitrosamines

Nitrosamines are a potential impurity in 53 ingredients
and more than 10,000 of the products listed in the
Environmental Working Group's Skin Deep database as of
July 2008. Due to the common nature of this impurity,
nearly every kind of personal care product, including
mascara, concealer, conditioner, baby shampoo, pain
relief salve and sunless tanning lotion, can contain
nitrosamines as an impurity. Nitrosamines have been
banned from use in cosmetics by Canada and the European
Union (ii).

Where It Comes From

Nitrosamines are created in cosmetics when nitrates and
various amino acids (the building blocks of proteins)
are in favorable conditions to combine. Specifically,
nitrosamines form when certain proteins, such as
diethanolamine (DEA) or triethanolamine (TEA), are used
in the same products as preservatives that can break
down into nitrates. As these various compounds break
down over time, they can recombine into nitrosamines.
Both DEA and TEA are common additives used to adjust the
pH or act as wetting agents (iii). The inadvertent
creation of this carcinogenic compound can add a whole
new challenge for consumers reading labels for safety,
since nitrosamines do not appear on a label, and the
precursor building blocks are not clearly noted.

Health Effects

Numerous studies and databases link nitrosamines to
cancer. They are listed as possible human carcinogens by
the U.S. Environmental Protection Agency, the
International Agency for Research on Cancer, the U.S.
National Toxicology Program Report on Carcinogens and
the California EPA Proposition 65 list of chemicals
known to cause cancer or birth defects. Several other
databases cite strong to moderate evidence regarding the
cancer-causing properties of nitrosamines. In addition,
there is some evidence of endocrine disruption at very
low doses. Studies have also linked nitrosamines to
developmental or reproductive toxicity, immunotoxicity,
neurotoxicity and systemic toxicity.

The FDA began watching personal care products for
nitrosamines in 1979, and published a report stating
that products containing nitrosamines could be seen as
adulterated and subject to FDA enforcement. This led to
a striking drop (from 150 ppm to 3 ppm) in
concentrations of one form of nitrosamine – n-nitrosoethanolmaine
(NDELA) – in testing 12 years later (iv). NDELA
accumulates in the liver, bladder and other organs and
leads to chronic toxic health effects. It is readily
absorbed through the skin (v).

In 1996, the FDA encouraged cosmetic manufacturers to
voluntarily remove ingredients that could combine to
form NDELA and to conduct testing to understand why
cosmetics become contaminated with NDELA. Despite these
encouragements, the Environmental Working Group found
that one in every 10 products contains ingredient that
can combine with others to form nitrosamines. A 1998
study by the UK Department of Trade and Industry showed
that nitrosamine levels in some products actually
increase in the months after a product is opened (vi).